<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="main" class="float">
    <div id="main-wrap">main</div>
  </div>
  <div id="left" class="float">left</div>
  <div id="right" class="float">right</div>
  <style>
    .float {
      float: left;
    }
    #main {
      width: 100%;
      height: 200px;
      background-color: chartreuse;
    }
    #main-wrap {
      margin: 0 150px 0 200px;
    }
    #left {
      margin-left: -100%;
      width: 200px;
      height: 200px;
      background-color: chocolate;
    }
    #right {
      margin-left: -150px;
      width: 150px;
      height: 200px;
      background-color: crimson;
    }
  </style>  
</body>
</html>